Photoredox-Catalyzed Dimerization of Arylalkenes via an Oxidative [4+2] Cycloaddition Sequence: Synthesis of Naphthalene Derivatives

Article abstract of DOI:10.1002/adsc.201600587

We report a radical cation [4+2] annulation of arylalkenes to afford naphthalene derivatives using an organic photosensitizer (9-mesityl-10-methylacridinium perchlorate) under visible light photocatalysis. In the presence of oxygen (in the air), the oxidative dimerization/intramolecular [4+2] cycloaddition of two alkene molecules provides 3,4-dihydronaphthalen-1(2H)-ones in good to high yields. Under a nitrogen atmosphere, (dihydro)naphthalenes were attained in moderate to excellent yields by using Selectfluor as the oxidant. The transformation proceeds via a tandem dimeric electrophilic addition/Friedel–Crafts cyclization/radical coupling/elimination sequence. This approach represents a mild and straightforward assembly of the naphthalene skeleton using a visible light photocatalytic cascade strategy. (Figure presented.).

Full text of DOI:10.1002/adsc.201600587

UPDATES
DOI: 10.1002/adsc.201600587
Photoredox-Catalyzed Dimerization of Arylalkenes via an
Oxidative [4+2] Cycloaddition Sequence: Synthesis of
Naphthalene Derivatives
Donglei Wei,a Yanru Li,a and Fushun Lianga,b,*
a
Department of Chemistry, Northeast Normal University, Changchun 130024, Peopleꢀs Republic of China
Fax. (+86)-431-8509-9759; phone. (+86)-431-8509-9759
E-mail: liangfs112@nenu.edu.cn
College of Chemistry, Liaoning University, Shenyang 110036, Peopleꢀs Republic of China
b
Received: June 4, 2016; Revised: September 4, 2016; Published online: && &&, 0000
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201600587.
Abstract: We report a radical cation [4+2] annula-
tion of arylalkenes to afford naphthalene deriva-
tives using an organic photosensitizer (9-mesityl-10-
methylacridinium perchlorate) under visible light
photocatalysis. In the presence of oxygen (in the
air), the oxidative dimerization/intramolecular
[4+2] cycloaddition of two alkene molecules pro-
vides 3,4-dihydronaphthalen-1(2H)-ones in good to
high yields. Under a nitrogen atmosphere, (dihy-
dro)naphthalenes were attained in moderate to ex-
cellent yields by using Selectfluor as the oxidant.
The transformation proceeds via a tandem dimeric
electrophilic addition/Friedel–Crafts cyclization/rad-
ical coupling/elimination sequence. This approach
represents a mild and straightforward assembly of
the naphthalene skeleton using a visible light photo-
catalytic cascade strategy.
erated are expected to possess unusual reactivities
compared to neutral alkenes. For example, a carbocat-
ion is responsible for an electrophilic reaction, and
a carbon radical can undergo radical addition or cou-
pling. As such, Nicewicz and co-workers developed
an elegant anti-Markovnikov olefin hydrofunctionali-
zation under photochemical conditions, employing
a dual catalyst system comprised of an organic single
electron photooxidant and a redox-active H-atom
donor (Scheme 1a).[4] In 2012, Yoon and co-workers
Keywords: cascade reaction; [4+2] cycloaddition;
naphthalene derivatives; radical cations; styrene de-
rivatives; visible light photocatalysis
Introduction
Alkenes are important building blocks in synthetic
chemistry, as they generally undergo addition and
polymerization reactions under thermal conditions.[1]
In the past decade, visible light photocatalysis has at-
tracted considerable attention due to the environmen-
tal compatibility and versatility in promoting a large
number of synthetically important reactions.[2] Under
photocatalytic conditions, alkene precursors are readi-
ly oxidized or reduced to polar radical species via
photoinduced electron transfer (PET) processes.[3] For
Scheme 1. Photocatalyzed reactions of alkenes based on rad-
electron-rich alkenes, the radical cations that are gen- ical cation intermediate.
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reported on visible light-mediated transition metal can be found in many lignans, a class of natural prod-
(Ru)-catalyzed [2+2] cycloaddition reactions based ucts existing in plants.[10] Due to their biological im-
on radical cation intermediates.[5a] Afterwards, the [2 portance and application as organic synthons, their
+ 2] dimerization of alkenes via an organic single synthesis has attracted considerable attention.[11]
electron oxidant-electron relay system was presented Herein, a mild and straightforward assembly of the
by Nicewicz et al. (Scheme 1b).[5b] As claimed in their naphthalene skeleton starting from simple styrene de-
work, when a photocatalyst with a high reduction po- rivatives, via a photocatalyzed cascade process of
tential was used, cycloreversion was accompanied in electrophilic addition/Friedel–Crafts cyclization/radi-
the [2+2] cycloaddition reactions of alkenes. In our cal coupling/elimination, has been developed.
research, we wish to achieve the oxidative linear ho-
mocoupling of alkenes and further transformations
through the selection of an appropriate photocatalyst. Results and Discussion
As a result, we found a new, formal [4+2] annulation
of arylalkenes under photoirradiated conditions with Initially, we performed the reaction of styrene 1a
an organic photosensitizer, Acr+-Mes (9-mesityl-10- (Eox = +1.97 V vs. SCE)[12] in the open air under dif-
methylacridinium perchlorate).[6] With the incorpora- ferent reaction conditions (Table 1). With 1 mol% of
tion of a keto functionality during the annulation cas- Acr+-Mes (E*red = +2.08 V vs. SCE)[12] as the organic
cade sequence, 3,4-dihydronaphthalen-1(2H)-ones photocatalyst, various solvents were screened (en-
were assembled in the open air whereas, under an N2 tries 1–6). No reaction occurred in polar solvents such
atmosphere, (dihydro)naphthalenes were constructed as DMSO (entry 1), and only a benzaldehyde side
efficiently by using Selectfluor as the oxidant product was observed in DMF solution (entry 2). In
(Scheme 1c).[7] 3,4-Dihydronaphthalen-1(2H)-ones (1- THF, we detected the formation of the addition/cycli-
tetralones) are found in natural products that exhibit zation product 2a, although the yield was low
interesting biological, pharmaceutical and medicinal (entry 3). Dichloromethane and nitromethane gave
properties.[8] 3,4-Dihydronaphthalen-1(2H)-one and improved yields (entries 4 and 5), and an even better
its substituted derivatives are also important starting yield of 62% was obtained in acetonitrile (entry 6).
materials and intermediates in organic synthesis.[9] On Considering that dioxygen is required in the catalytic
the other hand, the (1,2-dihydro)naphthalene skeleton cycle (see the Supporting 1nformation), we used an
Table 1. Optimization of the reaction conditions[a]
Entry
Catalyst
Co-oxidant
Solvent
Time [h]
Yield [%][b]
1
2
3
4
5
6
7
8
Acr+-Mes
Acr+-Mes
Acr+-Mes
Acr+-Mes
Acr+-Mes
Acr+-Mes
Acr+-Mes
Acr+-Mes
Acr+-Mes
Acr+-Mes
Acr+-Mes (5 mol%)
TPT
air
air
air
air
air
air
DMSO
DMF
THF
DCM
MeNO2
MeCN
MeCN
MeCN
MeCN (0.1 M)
MeCN (1.0 M)
MeCN
48
48
48
48
48
40
24
40
40
24
40
40
48
48
48
n.r.
0
21
30
59
62
60
87
84
71
76
32
n.r.
n.r.
n.r.
O2 balloon
air, PMN
air, PMN
air, PMN
air, PMN
air, PMN
air, PMN
air, PMN
PMN
9
10
11
12
13
14[c]
15[d]
MeCN
MeCN
MeCN
MeCN
none
Acr+-Mes
Acr+-Mes
[a]
Reactions were conducted with 1a (0.5 mmol), catalyst (1 mol%), and PMN (20 mol%) in 1.0 mL of dry solvent (0.5M)
at room temperature in the open air with a 12W blue LED irradiated, unless otherwise noted. n.r.=no reaction.
Isolated yield.
The reaction was conducted in the dark.
The reaction was conducted under an N2 atmosphere.
[b]
[c]
[d]
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O2 balloon to perform the reaction. However, a large afforded product 2a in 87% yield (entry 8). Encour-
amount of aldehyde side product was produced aged by these results, the solution concentration was
within 24 h (entry 7). We surmised that a high O2 con- changed. It was found that both higher and lower con-
centration may quench the radical cation intermediate centrations led to decreased yields (entries 9 and 10).
rapidly. With the introduction of PMN (2-phenylmalo- On increasing the catalyst amount to 5 mol%, the re-
nonitrile) as a co-oxidant, the reaction in the open air action turned out to be complicated, with 2a being
Table 2. Radical cation [4+2] annulation: synthesis of dihydronaphthalenones 2.[a,b,c,d]
[a]
Reactions were conducted with 1 mol% Acr+-Mes, and 20 mol% PMN in 0.5M MeCN in the open air with a 12W blue
LED.
Isolated yield.
[b]
[c]
Data in the parenthesis corresponds to the yield in the absence of PMN.
Arylaldehyde by-products can be observed in the reactions.
With DCM as the solvent.
[d]
[e]
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formed only in 76% yield (entry 11). The use of 2,4,6-
triphenylpyrylium tetrafluoroborate (TPT, 1 mol%)
(E*red = +2.28 V vs. SCE)[12] was also examined as the
organic photosensitizer, rather than Acr+-Mes, but
the yield decreased significantly (entry 12). Compara-
tively, in the absence of the photosensitizer, light or
air, no target molecule was observed, validating the
photocatalytic nature of this process (entries 13–15).
We next investigated the scope of the radical cation
[4+2] annulation reaction. It was found that various
substituted styrenes (Eox = +1.15~2.50 V vs. SCE for
Scheme 3. The cation radical [4+2] annulation of 2-thienyl-
ethylene.
general alkenes)[12] are suitable precursors for the ex- (Scheme 3).[16,17] However, electron-poor 2-pyridyl-
plored reaction (Table 2).[13] Substrates with electron- ethylene failed to afford the corresponding [4+2] an-
donating methoxy, ethoxy and acetyloxy groups at the nulation product, similar to the result observed for 4-
4-position of the styrene gave the desired products, nitrostyrene. In the reaction of a non-terminal styrene
2b–d, in moderate to high yields. The structure of 2b and a conjugated diene such as trans-stilbene or (E)-
was confirmed by X-ray single-crystal diffraction.[14] buta-1,3-dien-1-ylbenzene, oxidative cleavage of the
Alkyl substituents on the phenyl ring include o-, m-, C=C double bond to yield the corresponding benzal-
p-methyl, 2,4-dimethyl, tert-butyl and chloromethyl dehydes and cinnamaldehyde was observed. No reac-
(2e–j). Note that an inseparable regioisomer mixture tion takes place when an enyne (e.g., but-3-en-1-yn-1-
of 2f and 2f’ was obtained with a 3-methylstyrene ylbenzene) was used as the substrate under otherwise
substrate. Halogens (F, Cl, and Br) were well tolerat- identical conditions.
ed, giving the corresponding dihalogenated products
The cross-over radical cation [4+2] reaction using
2k–n in good yields. Interestingly, 1-vinyl- and 2-vinyl- two styrenes with different substituents on the phenyl
naphthalene also worked well, affording the corre- ring (e.g., a 1:1 mixture of 4-methylstyrene and 4-fluo-
sponding 2,3-dihydrophenanthrenone and 3,4-dihy- rostyrene) was also conducted (Scheme 4). The corre-
droanthracenone (2o and 2p) in 85% and 86% yield, sponding homodimerized and cross-dimerized prod-
respectively.[15]
ucts 2e, 2r and 2k were obtained as an inseparable
Styrenes containing a strong electron-withdrawing mixture in a 72% total isolated yield.[18]
group, such as a nitro group, were unable to react
To reveal the source of the ketone oxygen, we per-
under the standard conditions. Only trace amounts of formed the photoredox reaction of 1a in the presence
4-nitrobenzaldehyde were produced. This indicates of H218O (5.0 equiv.) (Scheme 5). As a result, dihydro-
that the generation of the corresponding radical naphthalenone 2a was produced in 79% yield without
cation is feasible but that the intermolecular electro- any 18O enrichment of its ketone oxygen. Together
philic addition is difficult due to the electron-poor with the experimental results of the reaction conduct-
character of 4-nitrostyrene. a-Methylstyrene and b-
methylstyrene were not competent partners. Aceto-
phenone and benzaldehyde were generated, along
with intact substrates. It seems that the quenching of
the resulting radical cation by molecular oxygen to
give the aldehyde product is much faster than the
[4+2] annulation reaction in this case. 1,1-Diphenyl-
ACHTUNGTRENNUNGethene could afford 4,4-diphenyl-3,4-dihydronaphtha-
len-1(2H)-one (2q), but in low yield (Scheme 2). Het-
eroarylalkenes were also subjected to the reaction se-
quence. As a result, the reaction of 2-thienylethene
performed in the open air gave 4-(thiophen-2-yl)-5,6-
dihydrobenzo[b]thiophen-7(4H)-one (3) in 38% yield
Scheme 4. Cross-over radical cation [4+2] reaction. Yields
Scheme 2. The cation radical [4+2] annulation of 1,1-diphe-
nylethene.
refer to the combined yields of all tetralone products. Ratio
1
was determined by H NMR analysis of the crude product.
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2a as the final product. On the other hand, the malo-
nonitrile radical that is derived from the H-atom
donor PMN would oxidize the organic photosensitizer
to finish the photoredox catalytic cycle. The malono-
nitrile anion would then accept a proton to complete
the organocatalytic cycle.
We also investigated the oxidative [4+2] cycloaddi-
tion reaction under an N2 atmosphere (for the optimi-
zation conditions, see the Supporting Information,
Table S1). In the presence of Selectfluor (0.5 equiv.),
Scheme 5. Control experiments.
ed under an N2 atmosphere (Table 1, entry 15), it was various dihydronaphthalenes 4a–e were obtained in
concluded that the ketone oxygen originates from good to high yields (80–92%, Table 3). It was found
molecular oxygen in the air (see the Supporting Infor- that naphthalenes 5a and 5b were produced when
mation, Scheme S1).
1.0 equiv. of Selectfluor was used. Similar to the re-
On the basis of all the results described above and sults mentioned above, only electron-rich terminal al-
previous work by Nicewicz[4] and Yoon,[5] we propose kynes are efficient for the radical cation [4+2] annula-
a plausible mechanism for the formation of naphtha- tions. The possible mechanism for the formation of
lenones (Scheme 6). Under irradiation, the acridinium 1,2-dihydronaphthalenes 4 and naphthalenes 5 is de-
catalyst is excited to (Acr+-Mes)* which oxidizes the picted in Scheme 7. The reaction involves a sequential
alkene 1a, generating a 1,2-radical cation A and the electrophilic addition, Friedel–Crafts cyclization, fluo-
reduced acridine radical. Electrophilic trapping of in- rination and HF elimination. In the case of 1.0 equiv.
termediate A by a neutral alkene molecule gives rise of Selectfluor, 1,2-dihydronaphthalenes 4 were oxi-
to distal 1,4-radical cation B, which readily undergoes dized to yield naphthalenes 5 via dehydrogenative ar-
Friedel–Crafts annulation to form intermediate C via omatization. A fluorine atom transfer[21] was proposed
deprotonation. Radical C would further react with as the key factor for the formation of (1,2-dihydro)-
triplet O2 to produce peroxide radical D.[19] The H-
atom transfer from PMN to intermediate D followed
Table 3. Radical cation [4+2] annulation: synthesis of (dihy-
by the elimination of water[20] affords naphthalenone
dro)naphthalenes 4 and 5.[a,b]
[a]
Reactions were conducted with 1 mol% Acr+-Mes,
20 mol% PMN, 0.5 equiv. Selectfluor in 0.1M MeCN
Scheme 6. Proposed cascade mechanism for the formation
of dihydronaphthalenones 2. HAT=hydrogen atom trans-
fer.
under N2 with a 12W blue LED for 12 h.
Isolated yield.
1.0 equiv. Selectfluor was used.
[b]
[c]
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and with Selectfluor as the oxidant, (dihydro)naph-
thalenes were attained in moderate to excellent
yields. The photocatalytic cascade protocol represents
a novel, mild and straightforward approach towards
synthesizing naphthalene derivatives including 3,4-di-
hydronaphthalen-1(2H)-ones,
dihydronaphthalenes
and naphthalenes starting from simple styrene deriva-
tives.
Experimental Section
General
Dry reagents were purchased from commercial sources and
used without further treatment. The products were purified
by column chromatography over silica gel. 1H NMR and
13C NMR spectra were recorded at 258C on a Varian spec-
trometer at 500 MHz and 125 MHz, respectively, with TMS
as the internal standard. Elemental analyses were measured
on an E-2400 analyzer (Perkin–Elmer). Mass spectra were
recorded on an Agilent 1100 LCMsD mass spectrometer.
Synthesis and Analytical Data of 2–5
Scheme 7. Proposed cascade mechanism for the formation
of (dihydro)naphthalenones 4 and 5. FAT=fluorine atom
transfer.
General procedure for the preparation of 2a–q and 3 (2a as
an example): To a solution of 9-mesityl-10-methylacridinium
perchlorate (1 mol%, 4.2 mg) and 2-phenylmalononitrile
(20 mol%, 28.4 mg) in dry MeCN (2.0 mL, with 4ꢂ MS),
styrene 1a (1.0 mmol, 104.2 mg) was added. The reaction
mixture was stirred at room temperature and irradiated by
a 12W blue LED for 40 h. After the starting material 1a
had been consumed as indicated by TLC, the reaction mix-
ture was poured into water and then extracted with CH2Cl2
(3ꢃ10 mL). The combined organic phase was washed with
water (3ꢃ10 mL), dried over anhydrous MgSO4, filtered
and concentrated under reduced pressure. The crude prod-
naphthalenes. In an isolated reaction of 2-phenylma-
lononitrile with Selectfluor (1.0 equiv.), 2-fluoro-2-
phenylmalononitrile could be obtained in 60% yield
(see the Supporting Information, Figure S1), which
partly supports the involvement of 2-fluoro-2-phenyl-
malononitrile in the proposed mechanism.
Finally, we tried to synthesize the bioactive bisnor-
ACHTUNGTRENNUNG
lignans pachypostaudin-A and pachypostaudin-B[22] uct was purified by flash chromatography (silica gel, petrole-
um ether:ethyl acetate=100:1) to give 2a as a white solid;
yield: 96.6 mg (87%).
utilizing the photocatalytic cascade protocol, but were
unsuccessful (see the Supporting Information,
Scheme S2).
General procedure for the preparation of 4 (4b as an ex-
ample): To a solution of 9-mesityl-10-methylacridinium per-
chlorate (1 mol%, 4.2 mg), 2-phenylmalononitrile (20 mol%,
28.4 mg) and Selectfluor (0.5 equiv., 177.1 mg) in dry MeCN
(10 mL), 4-methylphenylene 1e (1.0 mmol, 118.2 mg) was
added. The mixture was degassed using three freeze-pump-
thaw cycles under nitrogen. The reaction mixture was stirred
at room temperature and irradiated by a 12W blue LED for
Conclusions
In conclusion, we have developed a mild and straight-
forward approach for the construction of naphthalene
derivatives starting from simple styrene derivatives 12 h. After the starting material 1e had been consumed as
indicated by TLC, the reaction mixture was poured into
water and then extracted with CH2Cl2 (3ꢃ10 mL). The com-
bined organic phase was washed with water (3ꢃ10 mL),
dried over anhydrous MgSO4, filtered and concentrated
under reduced pressure. The crude product was purified by
flash chromatography (silica gel, petroleum ether) to give
4b as a colorless oil; yield: 100.7 mg (86%).
4-Phenyl-3,4-dihydronaphthalen-1(2H)-one (2a): White
solid; yield: 97 mg (87%); mp 70–728C; 1H NMR
(500 MHz, CDCl3): d=2.29–2.34 (m, 1H), 2.44–2.51 (m,
under visible light photoredox conditions. A variety of
substituted arylalkenes and 2-thienylethylene afforded
the corresponding formal [4+2] annulation products
in high efficiency. A mechanism involving electrophil-
ic addition/Friedel–Crafts cyclization/radical coupling/
elimination was proposed. On the one hand, in the
presence of oxygen (in the air), the oxidative dimeri-
zation/[4+2] cycloaddition of two alkene molecules
provided dihydronaphthalenones in good to high
yields. On the other hand, under an N2 atmosphere 1H), 2.59–2.65 (m, 1H), 2.70–2.76 (m, 1H), 4.29–4.32 (m,
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1H), 6.98 (d, J=7.5 Hz, 1H), 7.11 (d, J=7.5 Hz, 2H), 7.25–
7.27 (m, 1H), 7.31–7.37 (m, 3H), 7.43 (t, J=7.0 Hz, 1H),
8.12 (d, J=7.0 Hz, 1H); 13C NMR (125 MHz, CDCl3): d=
31.8, 36.7, 45.3, 126.8, 127.0, 127.1, 128.6, 128.6, 129.5, 132.8,
133.6, 143.7, 146.3, 198.1; HR-MS (ESI): m/z=223.1118,
calcd. for C16H14O [M+H]+: 223.1123.
44.9, 125.0, 125.3, 125.6, 126.9, 127.1, 127.3, 127.4, 128.3,
128.4, 128.9, 129.2, 129.5, 132.5, 133.2, 134.5, 135.7, 136.6,
137.0, 138.1, 138.2, 141.4, 143.4, 143.5, 143.8, 198.5, 198.9;
HR-MS (ESI): m/z=251.1445, 251.1441, calcd. for C18H18O
[M+H]+: 251.1436.
8-Methyl-4-(o-tolyl)-3,4-dihydronaphthalen-1(2H)-one
1
6-Methoxy-4-(4-methoxyphenyl)-3,4-dihydronaphthalen-
1(2H)-one (2b): White solid; yield: 114 mg (81%); mp 119–
(2g): Colorless oil; yield: 80 mg (64%); H NMR (500 MHz,
CDCl3): d=2.22–2.25 (m, 1H), 2.36–2.40 (m, 1H), 2.42 (s,
3H), 2.61–2.66 (m, 1H), 2.71 (s, 3H), 2.72–2.76 (m, 1H),
4.50–4.53 (m, 1H), 6.76 (d, J=8.0 Hz, 1H), 6.81 (d, J=
7.5 Hz, 1H), 7.08–7.17 (m, 3H), 7.22–7.27 (m, 2H);
13C NMR (125 MHz, CDCl3): d=19.6, 23.5, 29.3, 38.6, 42.4,
126.2, 126.6, 127.4, 128.6, 130.6, 130.8, 131.8, 132.4, 135.9,
141.1, 142.1, 147.7, 200.3; HR-MS (ESI): m/z=251.1429,
calcd. for C18H18O [M+H]+: 251.1436.
1
1208C; H NMR (500 MHz, CDCl3): d=2.23–2.28 (m, 1H),
2.40–2.44 (m, 1H), 2.54–2.60 (m, 1H), 2.64–2.70 (m, 1H),
3.75 (s, 3H), 3.81 (s, 3H), 4.19–4.21 (m, 1H), 6.44 (d, J=
2.5 Hz, 1H), 6.87 (d, J=8.5 Hz, 3H), 7.04 (d, J=8.5 Hz,
2H), 8.09 (d, J=8.5 Hz, 1H); 13C NMR (125 MHz, CDCl3):
d=32.0, 36.4, 44.8, 55.3, 55.4, 113.2, 113.6, 114.0, 126.5,
129.5, 129.6, 135.5, 149.1, 158.4, 163.7, 197.1; HR-MS (ESI):
m/z=283.1343, calcd. for C18H18O3 [M+H]+: 283.1334.
6-Ethoxy-4-(4-ethoxyphenyl)-3,4-dihydronaphthalen-
1(2H)-one (2c): White solid; yield: 85 mg (55%); mp 95–
968C; 1H NMR (500 MHz, CDCl3): d=1.37 (t, J=8.0 Hz,
3H), 1.42 (t, J=7.0 Hz, 3H), 2.20–2.27 (m, 1H), 2.37–2.43
(m, 1H), 2.53–2.59 (m, 1H), 2.64–2.70 (m, 1H), 3.93–3.98
(m, 2H), 4.00–4.04 (m, 2H), 4.16–4.19 (m, 1H), 6.42 (d, J=
2.0 Hz, 1H), 6.83–6.86 (m, 3H), 7.02 (d, J=9.0 Hz, 2H),
8.07 (d, J=9.0 Hz, 1H); 13C NMR (125 MHz, CDCl3): d=
14.6, 14.8, 32.0, 36.5, 44.8, 63.4, 63.6, 113.5, 114.1, 114.5,
126.3, 129.5, 129.5, 135.4, 149.2, 157.7, 163.1, 197.1; HR-MS
(ESI): m/z=311.1641, calcd. for C20H22O3 [M+H]+:
311.1647.
4-(7-Acetoxy-4-oxo-1,2,3,4-tetrahydronaphthalen-1-yl)-
phenyl acetate (2d): White solid; yield: 123 mg (73%); mp
62–638C; 1H NMR (500 MHz, CDCl3): d=2.25 (s, 3H),
2.27–2.30 (m, 1H), 2.31 (s, 3H), 2.43–2.47 (m, 1H), 2.60–
2.67 (m, 1H), 2.72–2.77 (m, 1H), 4.28–4.31 (m, 1H), 6.69 (d,
J=2.0 Hz, 1H), 7.07 (d, J=9.0 Hz, 2H), 7.09–7.11 (m, 1H),
7.14 (d, J=8.5 Hz, 2H), 8.16 (d, J=9.0 Hz, 1H); 13C NMR
(125 MHz, CDCl3): d=21.1, 21.1, 32.0, 36.9, 45.0, 120.9,
121.9, 122.2, 129.2, 129.5, 130.5, 140.7, 148.0, 149.5, 154.6,
168.8, 169.5, 196.7; HR-MS (ESI): m/z=339.1226, calcd. for
C20H18O5 [M+H]+: 339.1232.
4-(2,5-Dimethylphenyl)-5,8-dimethyl-3,4-dihydronaphtha-
len-1(2H)-one(2h): White solid; yield: 86 mg (62%); mp 96–
1
988C; H NMR (500 MHz, CDCl3): d=1.98 (s, 3H), 2.04–
2.09 (m, 1H), 2.11 (s, 3H), 2.42–2.45 (m, 1H), 2.46 (s, 3H),
2.47–2.49 (m, 1H), 2.64–2.69 (m, 1H), 2,71 (s, 3H), 4.53–
4.55 (m, 1H), 6.34 (s, 1H), 6.92 (d, J=7.5 Hz, 1H), 7.10 (t,
J=7.5 Hz, 2H), 7.20 (d, J=7.5 Hz, 1H); 13C NMR
(125 MHz, CDCl3): d=18.9, 19.2, 21.1, 23.7, 27.4, 35.3, 38.5,
127.1, 128.5, 130.6, 130.7, 132.3, 132.6, 134.4, 134.7, 135.2,
138.8, 139.5, 145.4, 201.2; HR-MS (ESI): m/z=279.1758,
calcd. for C20H22O [M+H]+: 279.1749.
6-(tert-Butyl)-4-[4-(tert-butyl)phenyl]-3,4-dihydronaphtha-
len-1(2H)-one (2i): White solid; yield: 130 mg (78%); mp
99–1008C; 1H NMR (500 MHz, CDCl3): d=1.24 (s, 9H),
1.32 (s, 9H), 2.26–2.31 (m, 1H), 2.45–2.57 (m, 2H), 2.61–
2.67(m, 1H), 4.29–4.31 (m, 1H), 7.00 (d, J=8.5 Hz, 2H),
7.05 (s, 1H), 7.32 (d, J=8.0 Hz, 2H), 7.39–7.41(m, 1H), 8.05
(d, J=8.5 Hz, 1H); 13C NMR (125 MHz, CDCl3): d=30.9,
31.3, 31.7, 34.4, 35.1, 36.0, 44.6, 124.3, 125.3, 126.4, 126.9,
128.1, 130.5, 140.4, 145.9, 149.4, 157.3, 198.2; HR-MS (ESI):
m/z=335.2366, calcd. for C24H30O [M+H]+: 335.2375.
6-(Chloromethyl)-4-[4-(chloromethyl)phenyl]-3,4-dihydro-
naphthalen-1(2H)-one (2j): Colorless oil; yield: 83 mg
1
(52%); H NMR (500 MHz, CDCl3): d=2.27–2.31 (m, 1H),
6-Methyl-4-(p-tolyl)-3,4-dihydronaphthalen-1(2H)-one
(2e): Colorless oil; yield: 103 mg (82%); 1H NMR
(500 MHz, CDCl3): d=2.23–2.27 (m, 1H), 2.92 (s, 3H), 2.35
(s, 3H), 2.41–2.46 (m, 1H), 2.55–2.60 (m, 1H), 2.66–2.72 (m,
1H), 4.22–4.24 (m, 1H), 6.81 (s, 1H), 6.99 (d, J=8.0 Hz,
2H), 7.14 (d, J=8.0 Hz, 2H), 7.17 (s, 1H), 8.01 (d, J=
8.0 Hz, 1H); 13C NMR (125 MHz, CDCl3): d=21.0, 21.8,
31.9, 36.4, 44.8, 127.2, 128.0, 128.5, 129.3, 129.9, 130.5, 136.3,
140.7, 144.5, 146.4, 198.1; HR-MS (ESI): m/z=251.1443,
calcd. for C18H18O [M+H]+: 251.1436.
7-Methyl-4-(m-tolyl)-3,4-dihydronaphthalen-1(2H)-one
(2f) and 5-methyl-4-(m-tolyl)-3,4-dihydronaphthalen-1(2H)-
one (2f’): White solid; yield: 104 mg (83%); 1H NMR
(500 MHz, CDCl3): d=2.10 (s, 3H), 2.23–2.27 (m, 2H),
2.28(s, 3H), 2.32 (s, 3H), 2.38 (s, 3H), 2.40–2.46 (m, 2H),
2.56–2.58 (m, 2H), 2.59–2.63(m, 1H), 2.69–2.75 (m, 1H),
4.21–4.23 (m, 1H), 4.42 (d, J=2.5 Hz, 1H), 6.76 (d, J=
7.5 Hz, 1H), 6.83 (s, 1H), 6.88 (t, J=7.5 Hz, 2H), 6.93 (s,
1H), 7.02 (d, J=7.5 Hz, 1H), 7.07 (d, J=7.5 Hz, 1H), 7.14
(t, J=7.5 Hz, 1H), 7.20 (t, J=7.5 Hz, 1H), 7.24–7.26 (m,
1H), 7.31 (t, J=7.5 Hz, 1H), 7.38 (d, J=7.0 Hz, 1H), 7.92
(s, 1H), 8.04(d, J=8.0 Hz, 1H); 13C NMR (125 MHz,
CDCl3): d=19.3, 20.9, 21.4, 21.4, 30.7, 31.9, 33.3, 36.8, 40.9,
2.45–2.49 (m, 1H), 2.59–2.65 (m, 1H), 2.69–2.75 (m, 1H),
4.31–4.33 (m, 1H), 4.49 (s, 2H), 4.60 (s, 2H), 6.99 (s, 1H),
7.11 (d, J=7.5 Hz, 2H), 7.37 (d, J=8.0 Hz, 2H), 7.40 (d, J=
8.0 Hz, 1H), 8.12 (d, J=8.0 Hz, 1H); 13C NMR (125 MHz,
CDCl3): d=31.7, 36.4, 44.9, 45.3, 45.8, 127.4, 127.8, 128.9,
129.0, 129.4, 132.6, 136.1, 142.9, 143.6, 146.2, 197.3; HR-MS
(ESI): m/z=319.0651, calcd. for C18H16Cl2O [M+H]+:
319.0656.
6-Fluoro-4-(4-fluorophenyl)-3,4-dihydronaphthalen-
1(2H)-one (2k): White solid; yield: 92 mg (71%); mp 67–
1
698C; H NMR (500 MHz, CDCl3): d=2.24–2.31 (m, 1H),
2.42–2.47 (m, 1H), 2.60–2.66 (m, 1H), 2.70–2.76 (m, 1H),
4.24–4.27 (m, 1H), 6.60–6.62 (m, 1H), 7.02–7.07 (m, 3H),
7.08–7.11 (m, 2H), 8.13–8.16 (m, 1H); 13C NMR (125 MHz,
CDCl3): d=31.9, 36.7, 44.9, 114.9, 115.6, 115.8, 129.3, 130.0,
130.3, 138.6, 149.3, 161.8, 165.9, 196.3; HR-MS (ESI): m/z=
259.0942, calcd for C16H12F2O [M+H]+: 259.0934.
8-Chloro-4-(2-chlorophenyl)-3,4-dihydronaphthalen-
1
1(2H)-one (2l): Colorless oil; yield: 59 mg (41%); H NMR
(500 MHz, CDCl3): d=2.34–2.37 (m, 1H), 2.42–2.44 (m,
1H), 2.68–2.71 (m, 2H), 4.82–4.84 (m, 1H), 6.83 (d, J=
7.5 Hz, 1H), 6.89 (d, J=7.5 Hz, 1H), 7.16 (t, J=7.0 Hz,
1H), 7.22 (t, J=7.0 Hz, 1H), 7.30 (t, J=7.5 Hz, 1H), 7.39
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(d, J=8.0 Hz, 1H), 7.45 (d, J=8.0 Hz, 1H); 13C NMR
(125 MHz, CDCl3): d=28.5, 37.7, 42,6, 127.1, 128.3, 128.3,
130.0, 130.0, 130.6, 131.0, 133.0, 134.0, 134.3, 140.5, 147.9,
196.4; HR-MS (ESI): m/z=291.0348, calcd. for C16H12Cl2O
[M+H]+: 291.0343.
2.67 (m, 2H), 2.75–2.80 (m, 1H), 4.52–4.55 (m, 1H), 6.82 (d,
J=3.5 Hz, 1H), 6.86 (d, J=5.0 Hz, 1H), 6.96–6.98 (m, 1H),
7.22–7.23 (m, 1H), 7.60 (d, J=5.0 Hz 1H); 13C NMR
(125 MHz, CDCl3): d=34.0, 36.6, 38.1, 124.3, 125.3, 126.8,
128.6, 133.9, 136.6, 145.6, 153.6, 191.5; HR-MS (ESI): m/z=
235.0244, calcd. for C12H10OS2 [M+H]+: 235.0251.
6-Chloro-4-(4-chlorophenyl)-3,4-dihydronaphthalen-
1(2H)-one (2m): White solid: yield: 105 mg (72%); mp 64–
1-Phenyl-1,2-dihydronaphthalene (4a): Colorless oil;
1
1
658C; H NMR (500 MHz, CDCl3): d=2.25–2.28 (m, 1H),
yield: 82 mg (80%); H NMR (500 MHz, CDCl3): d=2.62–
2.42–2.46 (m, 1H), 2.59–2.66 (m, 1H), 2.69–2.74 (m, 1H),
4.23–4.26 (m, 1H), 6.93 (d, J=1.0 Hz, 1H), 7.06 (d, J=
10.0 Hz, 2H), 7.31–7.35 (m, 3H), 8.05 (d, J=8.5 Hz, 1H);
13C NMR (125 MHz, CDCl3): d=31.6, 36.5, 44.6, 127.8,
128.9, 129.0, 129.2, 129.8, 131.1, 132.9, 140.1, 141.3, 147.3,
196.6; HR-MS (ESI): m/z=291.0350, calcd. for C16H12Cl2O
[M+H]+: 291.0343.
2.67 (m, 2H), 4.14 (t, J=8.5 Hz, 1H), 5.98–6.02 (m, 1H),
6.54 (d, J=9.5 Hz, 1H), 6.81 (d, J=7.5 Hz, 1H), 7.07–7.11
(m, 2H), 7.18 (t, J=7.5 Hz, 1H), 7.22–7.25 (m, 3H), 7.31 (t,
J=7.5 Hz, 2H); 13C NMR (125 MHz, CDCl3): d=31.9, 43.8,
126.1, 126.4, 126.8, 127.2, 127.2, 127.8, 128.0, 128.4, 128.4,
134.1, 137.8, 144.4; HR-MS (ESI): m/z=207.1169, calcd. for
C16H14 [M+H]+: 207.1174.
6-Bromo-4-(4-bromophenyl)-3,4-dihydronaphthalen-
1(2H)-one (2n): White solid; yield: 116 mg (61%); mp 86–
888C; H NMR (500 MHz, CDCl3): d=2.24–2.27 (m, 1H),
2.42–2.46 (m, 1H), 2.62–2.65 (m, 1H), 2.68–2.71 (m, 1H),
4.22–4.24 (m, 1H), 6.99 (d, J=8.5 Hz, 2H), 7.11 (s, 1H),
7.47–7.52 (m, 3H), 7.97 (d, J=8.5 Hz, 1H); 13C NMR
(125 MHz, CDCl3): d=31.6, 36.5, 44.7, 121.1, 129.0, 129.1,
130.2, 130.8, 131.5, 132.0, 132.2, 141.8, 147.3, 196.7; HR-MS
(ESI): m/z=380.9303, calcd. for C16H12Br2O [M+H]+:
380.9313.
7-Methyl-1-(p-tolyl)-1,2-dihydronaphthalene (4b): Color-
less oil; yield: 101 mg (86%); H NMR (500 MHz, CDCl3):
1
1
d=2.22 (s, 3H), 2.34 (s, 3H), 2.56–2.59 (m, 1H), 2.61–2.65
(m, 1H), 4.05 (t, J=8.5 Hz, 1H), 5.90–5.93 (m, 1H), 6.51 (d,
J=10 Hz, 1H), 6.66 (s, 1H), 6.97–7.01 (m, 2H), 7.07–7.13
(m, 4H); 13C NMR (125 MHz, CDCl3): d=21.0, 21.3, 32.2,
43.4, 126.0, 126.1, 127.3, 127.8, 128.2, 128.6, 129.1, 131.5,
135.9, 137.0, 137.9, 141.6; HR-MS (ESI): m/z=235.1495,
calcd. for C18H18 [M+H]+: 235.1487.
7-(tert-Butyl)-1-[4-(tert-butyl)phenyl]-1,2-dihydronaphtha-
lene (4c): White solid; yield: 146 mg (92%); mp 71–728C;
1H NMR (500 MHz, CDCl3): d=1.22 (s, 9H), 1.31 (s, 9H),
2.57–2.62 (m, 1H), 2.67–2.72 (m, 1H), 4.10 (t, J=8 Hz, 1H),
5.89–5.93 (m, 1H), 6.51 (d, J=9.5 Hz, 1H), 6.93 (s, 1H),
7.05 (d, J=8 Hz, 1H), 7.11 (d, J=8 Hz, 2H), 7.21 (dd, J=
2 Hz, J=8 Hz, 1H), 7.30 (d, J=8.5 Hz, 2H); 13C NMR
(125 MHz, CDCl3): d=31.2, 31.4, 32.0, 34.4, 34.6, 43.2,
123.5, 125.1, 125.3, 125.7, 126.3, 127.7, 127.8, 131.5, 137.3,
141.5, 148.9, 150.2; HR-MS (ESI): m/z=319.2430, calcd. for
C24H30 [M+H]+: 319.2426.
4-(Naphthalen-2-yl)-3,4-dihydroanthracen-1(2H)-one (2o):
1
White solid; yield: 137 mg (85%); mp 124–1268C; H NMR
(500 MHz, CDCl3): d=2.50–2.54 (m, 1H), 2.56–2.60 (m,
1H), 2.63–2.71 (m, 1H), 2.73–2.80 (m, 1H), 5.23–5.24 (m,
1H), 7.26 (d, J=8.5 Hz, 1H), 7.34–7.43 (m, 4H), 7.52 (t, J=
7.5 Hz, 1H), 7.57 (d, J=8.0 Hz, 1H), 7.78–7.82 (m, 2H),
7.87–7.91 (m, 3H), 8.28 (d, J=8.5 Hz, 1H); 13C NMR
(125 MHz, CDCl3): d=31.0, 33.2, 40.7, 122.6, 125.8, 126.0,
126.2, 126.6, 126.9, 126.9, 127.5, 127.7, 128.1, 128.3, 128.6,
128.8, 130.8, 131.1, 132.2, 133.2, 136.2, 139.6, 143.0, 198.7;
HR-MS (ESI): m/z=323,1425, calcd. for C24H18O [M+H]+:
323.1436.
5-Methyl-1-(o-tolyl)-1,2-dihydronaphthalene (4d): Color-
1
less oil; yield: 105 mg (90%); H NMR (500 MHz, CDCl3):
1-(Naphthalen-1-yl)-2,3-dihydrophenanthren-4(1H)-one
(2p): White solid; yield: 138 mg (86%); mp 124–1258C;
1H NMR (500 MHz, CDCl3): d=2.53–2.56 (m, 1H), 2.70–
2.81 (m, 3H), 5.31–5.32 (m, 1H), 6.89 (d, J=7.0 Hz, 1H),
7.14 (m, J=8.5 Hz, 1H), 7.30 (t, J=7.5 Hz, 1H), 7.53–7.59
(m, 3H), 7.70 (t, J=7.5 Hz, 1H), 7.77 (d, J=8.5 Hz, 1H),
7.82 (d, J=8.0 Hz, 1H), 7.89 (d, J=8.5 Hz, 1H), 7.93 (d, J=
8.0 Hz, 1H), 8.17. (d, J=8.5 Hz, 1H), 9.51 (d, J=8.5 Hz,
1H); 13C NMR (125 MHz, CDCl3): d=29.3, 37.8, 42.8, 123.3,
125.3, 125.8, 126.3, 126.4, 127.0, 127.2, 127.6, 127.7, 128.3,
128.4, 129.0, 129.2, 131.1, 131.4, 133.0, 134.2, 134.6, 138.7,
148.1, 200.7; HR-MS (ESI): m/z=323,1431, calcd. for
C24H18O [M+H]+: 323.1436.
d=2.36 (s, 3H), 2.39 (s, 3H), 2.53–2.58 (m, 2H), 4.34–4.38
(m, 1H), 6.06–6.10 (m, 1H), 6.54 (d, J=7.5 Hz, 1H), 6.78
(d, J=10 Hz, 1H), 6.95 (t, J=7.5 Hz, 1H), 7.02 (d, J=
7.5 Hz, 1H), 7.10 (t, J=5 Hz, 1H), 7.12–7.17 (m, 2H), 7.21
(t, J=4 Hz, 1H); 13C NMR (125 MHz, CDCl3): d=19.3,
19.8, 30.1, 40.0, 124.7, 125.3, 126.1, 126.2, 126.9, 127.6, 128.3,
128.5, 130.4, 132.6, 133.1, 136.2, 138.0, 142.1; HR-MS (ESI):
m/z=235.1480, calcd. for C18H18 [M+H]+: 235.1487.
5-Methyl-1-(o-tolyl)-1,2-dihydronaphthalene (4e): White
solid; yield: 119 mg (91%); mp 107–1088C; 1H NMR
(500 MHz, CDCl3): d=1.96 (s, 3H), 2.10 (s, 3H), 2.34–2.38
(m, 1H), 2.40 (s, 3H), 2.45 (s, 3H), 2.80–2.86 (m, 1H), 4.35
(d, J=9 Hz, 1H), 5.76–5.79 (m, 1H), 6.42 (s, 1H), 6.77 (dd,
J=3 Hz, J=10 Hz, 1H), 6.86 (d, J=7.5 Hz, 1H), 6.91 (d,
J=7.5 Hz, 1H), 6.99 (d, J=7.5 Hz, 1H), 7.05 (d, J=8 Hz,
1H); 13C NMR (125 MHz, CDCl3): d=18.8, 19.1, 19.3, 21.2,
29.7, 34.6, 124.9, 125.2, 126.7, 128.3, 128.7, 129.1, 130.1,
130.9, 131.6, 132.7, 133.4, 134.9, 135.7, 141.0; HR-MS (ESI):
m/z=263.1792, calcd. for C20H22 [M+H]+: 263.1800.
4,4-Diphenyl-3,4-dihydronaphthalen-1(2H)-one
(2q):
1
White solid; yield: 43 mg (29%); mp 168–1698C; H NMR
(500 MHz, CDCl3): d=2.53 (t, J=6.5 Hz, 2H), 2.97 (t, J=
6.5 Hz, 2H), 6.74–6.76 (m, 1H), 7.03–7.04 (t, 4H), 7.22–7.31
(m, 6H), 7.37–7.44 (m, 2H), 8.13–8.15 (m, 1H); 13C NMR
(125 MHz, CDCl3): d=35.7, 36.9, 53.3, 126.8, 127.2, 127.6,
128.2, 129.2, 130.9, 132.8, 133.1, 145.7, 149.6, 197.9; HR-MS
(ESI): m/z=299.1440, calcd. for C22H18O [M+H]+:
299.1436.
7-Fluoro-1-(4-fluorophenyl)naphthalene (5a): White solid;
yield: 78 mg (65%); mp 54–558C; 1H NMR (500 MHz,
CDCl3): d=7.18–7.22 (t, 2H), 7.27–7.30 (m, 1H), 7.42–7.50
(m, 5H), 7.86 (d, J=8.5 Hz, 1H), 7.89–7.92 (m, 1H);
13C NMR (125 MHz, CDCl3): d=109.2, 115.4, 116.2, 124.6,
127.7, 130.7, 131.4, 132.6, 136.2, 138.7, 160.0, 161.4, 161.9,
7-(Thiophen-2-yl)-6,7-dihydrobenzo[b]thiophen-4(5H)-
one (3): White solid; yield: 45 mg (38%); mp 95–968C;
1H NMR (500 MHz, CDCl3): d=2.37–2.41 (m, 1H), 2.55–
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163.4; HR-MS (ESI): m/z=241.0824, calcd. for C16H10F2
[M+H]+: 241.0829.
[5] Radical cation [2+2] cycloaddition: a) M. A. Ischay,
M. S. Ament, T. P. Yoon, Chem. Sci. 2012, 3, 2807;
b) M. Riener, D. A. Nicewicz, Chem. Sci. 2013, 4, 2625;
radical cation [4+2] cycloaddition: c) S. Lin, M. A.
Ischay, C. G. Fry, T. P. Yoon, J. Am. Chem. Soc. 2011,
133, 19350; d) S. Lin, C. E. Padilla, M. A. Ischay, T. P.
Yoon, Tetrahedron Lett. 2012, 53 3073; radical cation
[2+2+2] cycloaddition: e) J. D. Parrish, M. A. Ischay,
Z. Lu, S. Guo, N. R. Peters, T. P. Yoon, Org. Lett. 2012,
14, 1640.
7-(tert-Butyl)-1-[4-(tert-butyl)phenyl]naphthalene
(5b):
Colorless oil; yield: 128 mg (81%); 1H NMR (500 MHz,
CDCl3): d=1.33 (s, 3H), 1.42 (s, 3H), 7.04 (d, J=6.5 Hz,
1H), 7.44–7.52 (m, 5H), 7.59 (d, J=8.5 Hz, 1H), 7.79 (d, J=
7.5 Hz, 1H), 7.85 (d, J=8.5 Hz, 1H), 7.96 (s, 1H); 13C NMR
(125 MHz, CDCl3): d=31.2, 31.5, 34.6, 35.0, 121.1, 124.5,
124.8, 125.1, 126.9, 127.1, 127.9, 129.7, 131.4, 132.1, 137.9,
140.1, 148.5, 150.0; HR-MS (ESI): m/z=317.2262, calcd. for
C24H28 [M+H]+: 317.2269.
[6] The organic photocatalyst Acr+-Mes has found wide
applications in visible light-mediated reactions. For se-
lected examples, see: a) T.-T. Zeng, J. Xuan, W. Ding,
K. Wang, L.-Q. Lu, W.-J. Xiao, Org. Lett. 2015, 17,
4070; b) J. Xuan, X.-D. Xia, T.-T. Zeng, Z.-J. Feng, J.-
R. Chen, L.-Q. Lu, W.-J. Xiao, Angew. Chem. 2014,
126, 5759; Angew. Chem. Int. Ed. 2014, 53, 5653; c) X.
Wu, C. Meng, X. Yuan, X. Jia, X. Qian, J. Ye, Chem.
Commun. 2015, 51, 11864; d) J. D. Griffin, M. A.
Zeller, D. A. Nicewicz, J. Am. Chem. Soc. 2015, 137,
11340.
Acknowledgements
Financial support from the National Natural Science Founda-
tion of China (21172034 and 21372039) and the Fundamental
Research Funds for the Central Universities (2412015J006) is
gratefully acknowledged.
[7] During our own investigations, a similar work was re-
ported by Wang and co-workers, see: K. Wang, L.-G.
Meng, Q. Zhang, L. Wang, Green Chem. 2016, 18,
2864.
References
[1] F. A. Carey, R. J. Sundberg, Advanced Organic Chemis-
try, 5th edn., Springer, 2007.
[8] a) C. F. Schwender, S. Farber, C. Blaum, J. Shavel, J.
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Do Rosꢄrio, F. De Pilla Varotti, A. U. Krettli, Antimi-
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L. Tsai, A. G. Damu, P-C. Kuo, P-L. Wu, J. Nat. Prod.
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These are not the final page numbers!

UPDATES
Photoredox-Catalyzed Dimerization of Arylalkenes via an
Oxidative [4+2] Cycloaddition Sequence: Synthesis of
Naphthalene Derivatives
11
Adv. Synth. Catal. 2016, 358, 1 – 11
Donglei Wei, Yanru Li, Fushun Liang*
Adv. Synth. Catal. 0000, 000, 0 – 0
11
ꢁ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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These are not the final page numbers!